Thermal-Hydro-Mechanical Coupling Response Characteristics of Unsaturated Soil Under Complex Temperature Paths

The study of thermo-hydro-mechanical (THM) coupling in unsaturated soils under complex temperature paths is of significant importance in the fields of traffic geotechnics and engineering geology.This research modifies the classical soil-water characteristic curve model by incorporating the effects of porosity and temperature,thus providing a more accurate determination of the parameters involved in THM coupling numerical modeling.The accuracy and reliability of the numerical model were validated through comparison with experimental results.An analysis was conducted on the THM coupling response characteristics of unsaturated soil under two typical temperature paths of periodic cycle and exponential growth.The results indicate that under cyclic temperature loading,the temperature and saturation undergo cyclical changes that mirror the temperature load cycle.Phenomena such as phase lag and amplitude attenuation are observed within these cycles,with amplitude attenuation increasing with distance from the heat source.Additionally,the total displacement of measurement points exhibits cyclical changes in sync with the temperature load,without phase lag,and the amplitude of total displacement increases closer to the heat source.Under exponential growth temperature paths,the saturation and temperature of the measurement points first decrease and then increase.Points closer to the heat source show a greater degree of decrease and reach their lowest points earlier before rapidly rising to a stable stage.However,the total displacement curve evolves differently from the temperature curve.